1. Field of the Invention
The present invention relates to an original document reading-out apparatus in an image forming apparatus such as a copying machine, facsimile device, etc., and in particular, relates to a reading-out apparatus capable of reading out the front and rear surfaces of the original document and an image forming apparatus including therein the reading-out apparatus.
2. Discussion of the Background
In the past, as to the reading-out method of a two-sided reading-out apparatus in the image forming apparatus provided with an automatic document feeding apparatus (ADF), a scanning method of stopping the original document on the contact glass and scanning a portion of the original document and a sheet-through method of stopping the scanner and moving the original document are well known.
In the scanning method, since the original document is stopped in order on the contact glass, it needs a lot of time for the operator to exchange the original document. For this reason, in particular, it needs a lot of time to read out both surfaces of the original document, and therefore productivity is lowered. That is the defect to be solved. On the other hand, as to the sheet-through method, although the original document exchanging time can be shortened to the level not exerting any influence on the productivity, the process of turning over the original document is lengthy in order to arrange properly the page order after discharging the original document in the case of reading out the image of both surfaces of the original document, and therefore the productivity turns out to be lowered after all due to the processing time. That is a defect to be solved.
Furthermore, in the case of using the ordinary image forming apparatus, there exists either one of the scanning method and the sheet-through method as the reading-out method. In such situation, the original document feeding route of the automatic document feeder (ADF) carried in accordance with the reading-out method turns out to be determined.
Here, in the apparatus disclosed in the published specification of Japanese Laid-open Patent Publication No. 5-303246, the reading-out method of the image forming apparatus can be enabled to select, and the reading-out of the image on the original document can be made by changing over the original document feeding path of the ADF in accordance with the operational mode.
Furthermore, in the apparatus disclosed in the published specification of Japanese Laid-open Patent Publication No. 9-46483, because the original document is fed from one paper feeding opening (outlet), the scan reading-out and the sheet-through reading-out can be done.
Furthermore, in the copying system disclosed in the published specification of Japanese Laid-open Patent Publication No. 7-110641, the scan reading-out and the sheet-through reading-out can be done through one paper feeding opening (outlet) in consideration of the reading-out of the image on both sides of the original document.
Moreover, in the two-sided reading-out apparatus disclosed in the published specification of Japanese Published Patent No. 6-26416, the reading-out apparatus is provided with a movable reading-out unit which can be moved along the contact glass and a fixed reading-out unit disposed at the document advancing side or at the document discharging side of the document conveying belt for conveying the document put on the contact glass which is employed for reading out the opposite surface of the original document to the surface of the movable reading-out unit.
Furthermore, the published specification of Japanese Laid-open Patent Publication No. 1-194658 proposes an apparatus in which plural reading-out units are provided in order to improve the productivity in regard to the reading-out of both surfaces of the original document, and thereby the image on the first surface and that on the second surface are read out almost at the same time.